Highly-deviated well oil base drilling fluid borehole cleaning control method

Abstract

The invention discloses a highly-deviated well oil base drilling fluid borehole cleaning control method. The highly-deviated well oil base drilling fluid borehole cleaning control method includes thefollowing steps: S1, on the basis of well history data of a drilled well and relevant data of a new well, the new well is analyzed through drilling analysis software; S2, at a certain drilling parameter, the change situations of the thicknesses of a cuttings bed and the equivalent circulating density of drilling fluid under different drilling fluid performance are analyzed in a simulated mode; S3,data are monitored in real time in the drilling process, and the recorded data comprise, but not limited to, the hook load, the cuttings recovery ratio, the torque, the pump pressure, up-lifting anddown-lowering data, and ECD actual measured values; and S4, the borehole cleaning state is judged based on the actual monitored values of the S3, so that under the premise of maintaining the high blocking property of the drilling fluid and under the condition of meeting the capability of drilling equipment, the rheological property of the drilling fluid is adjusted until the actual values monitored in the S3 conform to the state of the cleaning standard. The area range where the annulus drilling fluid is located in a turbulent state is enlarged, the surge pressure and the equivalent circulating density of the drilling fluid are decreased, the mechanical drilling speed is released, and the operation efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling engineering, in particular to a method for controlling borehole cleaning of oil-based drilling fluid in highly deviated wells. Background technique [0002] At present, tapping the potential of mature offshore oil and gas fields mainly relies on the implementation of extended-reach wells in existing production facilities to develop marginal small oil fields far from the platform, so as to realize the economical and effective development of marginal oil and gas fields. With the continuous extension of extended-reach wells, the greater the inclination angle of the wellbore passing through the collapse-prone section, the longer the length of the inclination section, and the difficulty of maintaining the stability of the wellbore and the cleanliness of the wellbore also increases exponentially. [0003] In the previous drilling operation, it is generally believed that in order to increase t...

AI Technical Summary

Problems solved by technology

As the well depth increases, the circulation pressure loss increases, and the pump pressure gradually increases. The pump pressure generated by the high-viscosity drilling fluid is more likely to reach the upper limit of the mud pump pressure limit. In order to increase the intermediate completion depth of the technical well section, it is necessary to reduce Drilling displacement (thus reducing the pump pressure), so the return velocity of the drilling fluid annulus will be reduced, the flow state of the drilling fluid in the annulus is more inclined to laminar flow, and cuttings are more likely to accumulate, thus forming a cuttings bed, making it more difficult to clean the wellbore

[0005] With the increase of well inclination, the component of annular back velocity along the gravity direction gradually decreases, the eccentricity of drilling tool increases, and the drilling fluid flows to the high side of the wellbore more easily, so the flow rate of the drilling fluid at the low side of the wellbore decreases, and the cuttings accelerate to settle at the bottom of the wellbore. In the lower part of the annulus, the immobile zone of the cuttings bed formed on the lower side of the borehole widens. As the viscosity of the drilling fluid increases, it is difficult for the drilling fluid to reach a turbulent flow state, and the rock-carrying capacity decreases. The cuttings bed at the lower side of the borehole It will be further widened, and the cleaning effect of the wellbore can no longer meet the operational requirements; in the early drilling process of highly deviated wells, affected by the cuttings bed, tripping jams, pump holding, torque holding, and even lost circulation occurred frequently , stuck pipe and other accidents seriously affect the drilling efficiency and downhole safety of highly deviated wells

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